The present invention relates to a steering shaft assembly for motor vehicles such as automobiles or the like. More particularly, the invention concerns a steering shaft assembly comprising two complementary, interconnected shaft pieces adapted to be connected to the vehicle steering gear and steering wheel, respectively, which shaft pieces are arranged to be disconnected upon application of a predetermined axial force.
It is known to construct motor vehicle steering shaft assemblies with a divided, "breakaway" steering shaft to eliminate the possibility of penetration of the steering column into the region of the vehicle operator upon collision. Five references which disclose this type of arrangement are the U.S. Pat. Nos. 3,472,093; 3,760,649 and 3,752,007; and the West German patent publications (DOS) Nos. 1,927,173 and 2,106,963.
While the known safety steering shaft assemblies of the above-noted type are designed to transmit steering commands (i.e., torque) without distortion from the steering wheel to the steering gear, they may be troublseome if acted upon by bending moments originating with the steering gear. This is particularly true for shaft assemblies which comprise one or more universal joints permitting a plurality of shaft sections to be connected together in an articulated manner. In such cases the shafts connected to the steering wheel and steering gear, respectively, are not aligned on a common axis so that high momentary torques, which frequently occur during operation of the vehicle, are converted into severe bending moments.
It is the purpose of the present invention to provide a safety steering shaft assembly of the type having shaft connections which are disengaged on impact, such that the shaft assembly is capable of withstanding bending moments of the kind just described.